Recently, display devices that include a liquid crystal panel serving as a flat display unit having many features such as the reduced thickness and weight compared with a conventional cathode-ray tube (CRT), as typified by a liquid crystal display device, have become the mainstream of domestic television receivers, for example. Such a liquid crystal display device includes an illuminating device for emitting light (back light) and a liquid crystal panel that displays desired images by functioning as a shutter against the light from a light source provided in the illuminating device. In such a television receiver, information such a characters and images contained in television broadcasting video signals is displayed on the display screen of the liquid crystal panel.
Illuminating devices are broadly classified into direct type and edge light type, depending on the arrangement of the light source relative to the liquid crystal panel. Direct type illuminating devices, with which high brightness and large screen size are easier to achieve than with the edge light type, are normally employed for liquid crystal display devices including a liquid crystal panel of 20 inches or larger. Specifically, since the direct type illuminating device is configured by arranging a plurality of light sources on the rear side (non-display screen side) of the liquid crystal panel, the light sources can be arranged just behind the liquid crystal panel, and therefore it is possible to use a large number of light sources, thereby readily achieving high brightness. Therefore, the direct type illuminating device is suitable for achieving high brightness and large screen size. In addition, the inside of the direct type illuminating device is a hollow structure, so the weight of even a large size device can be suppressed. This is another reason why the direct type illuminating device is suitable for achieving high brightness and large screen size.
With the conventional direct type illuminating device as described above, as disclosed in JP 2002-231034A for example, it is proposed to provide a plurality of cold cathode fluorescent tubes as light sources, to connect an inverter circuit to each of the cold cathode fluorescent tubes, and to drive the cold cathode fluorescent tubes through high-frequency lighting by the inverter circuit.